Temperature behavior of the growth mechanism during layer epitaxial growth

Abstract

An analysis of epitaxial layer growth with a focus on its temperature dependence is presented, based on rate equations that account for an Ehrlich-Schwoebel (ES) effect. Numerical integration of the rate equations shows that ES barrier enhancement leads to a crossover from smooth layer-by-layer to rough multilayer growth. For a more reliable identification of this transition to diverging roughness, the model is extended to large times (up to fifty monolayers growth). A more accurate phase diagram of the homoepitaxial growth mode in the space of growth parameters (the adatoms surface diffusivity and the ES barrier) is then constructed. An analytic form for the first layer coverage kinetics up to a third layer nucleation is derived for the first time. The scaling with growth parameters is found for a critical coverage for the next layer nucleation that uniquely determines the growth mode transition. From the calculated temperature dependence of the critical coverage at various values of the activation energy for the adatom surface diffusion and the ES barrier, the growth mode behaviour with substrate temperature is obtained. The model predictions are compared with published Monte Carlo simulations. © 2008 IOP Publishing Ltd.